Source: U.S. Environmental Protection Agency
quote: This requirement isn't about preventing deaths from SO2 poisoning of humans, it's about preventing human deaths caused by SO2 poisoning of catalytic converters.Sulfur in the exhaust reduces the effectiveness of catalytic converters. Reducing the sulfur flowing over the catalyst substrate keeps the converter working better, longer, keeping smog out of the air.
quote: Lots of people in localities with regular exhaust system testing can tell you from firsthand experience that catalysts don't necessarily outlast the vehicle.
quote: In case my statement wasn't clear enough, I agree with you that nobody is dying from excessive SO2 inhalation from cars. Occasionally people complain about the smell. SO2 isn't the pollutant being blamed for deaths, but controlling it is the key to the claimed health benefits of this change. It's that tricky catalytic chemistry, so you have to be knowledgeable and think your way through it.
quote: P.S.- there's a subtext here for someone that hates Obama and green regulations and unions and Government Motors to pick up on if you're clever enough to spot it...... ;)